The relevance of mass spectrometry to decision making during brain surgery is discussed by scientists in the US who show that it can distinguish between necrotic tissue and viable regions of brain tumours, which will help to guide tumour resection. Writing in Journal of Mass Spectrometry, the team described how they used ambient mass spectrometry to analyse 12 surgical samples removed from a brain tumour, issuing a report within 9 days of the operation.

The results from desorption electrospray ionisation mass spectrometry (DESI MS) were carefully correlated with those from histopathology to identify necrotic tissue, which is a powerful indicator of high-grade malignancy. The same technique could discriminate between viable and necrotic tissue, relying on statistical analysis of the mass spectrometric profiles of lipids for differentiation.

The protocol could be applied to other tumour types, building up a library of the molecular signatures that correlate with various histological features to create tumour classifiers that can be used in real time conditions in the operating room. This will be aided by the development of smaller, portable mass spectrometers.

"As more and more is carried out, DESI-MS could have a significant role for a broad range of diagnostic applications including defining the boundaries between tumor and normal tissue, diagnosing image-guided needle biopsies, and determining prognostic and predictive information for guiding patient care," the team reported.

The fact that mass spectrometry is a destructive technique is irrelevant in this case, since the surgery itself disrupts tissue. The team has already sited an ambient mass spectrometer at the Advanced Multimodality Image Guided Operating (AMIGO) suite in Brigham and Women's Hospital. It is being used to "validate MS findings for a variety of surgical diseases tackled by the growing field of mass spectrometry imaging and to continue technology development with the hope of improving patient care."